Fish can recognize human faces, new study shows

A species of tropical fish has been shown to be able to distinguish between human faces. It is the first time fish have demonstrated this ability.

The research, carried out by a team of scientists from the University of Oxford (UK) and the University of Queensland (Australia), found that archerfish were able to learn and recognize faces with a high degree of accuracy—an impressive feat, given this task requires sophisticated visual recognition capabilities.

The study is published in the journal Scientific Reports.

First author Dr Cait Newport, Marie Curie Research Fellow in the Department of Zoology at Oxford University, said: 'Being able to distinguish between a large number of human faces is a surprisingly difficult task, mainly due to the fact that all human faces share the same basic features. All faces have two eyes above a nose and mouth, therefore to tell people apart we must be able to identify subtle differences in their features. If you consider the similarities in appearance between some family members, this task can be very difficult indeed.

'It has been hypothesized that this task is so difficult that it can only be accomplished by primates, which have a large and complex brain. The fact that the human brain has a specialized region used for recognizing human faces suggests that there may be something special about faces themselves. To test this idea, we wanted to determine if another animal with a smaller and simpler brain, and with no evolutionary need to recognize human faces, was still able to do so.'

The researchers found that fish, which lack the sophisticated visual cortex of primates, are nevertheless capable of discriminating one face from up to 44 new faces. The research provides evidence that fish (vertebrates lacking a major part of the brain called the neocortex) have impressive visual discrimination abilities.

Credit: University of Oxford

In the study, archerfish—a species of tropical fish well known for its ability to spit jets of water to knock down aerial prey - were presented with two images of human faces and trained to choose one of them using their jets. The fish were then presented with the learned face and a series of new faces and were able to correctly choose the face they had initially learned to recognize. They were able to do this task even when more obvious features, such as head shape and colour, were removed from the images.

The fish were highly accurate when selecting the correct face, reaching an average peak performance of 81% in the first experiment (picking the previously learned face from 44 new faces) and 86% in second experiment (in which facial features such as brightness and colour were standardized).

Dr Newport said: 'Fish have a simpler brain than humans and entirely lack the section of the brain that humans use for recognizing faces. Despite this, many fish demonstrate impressive visual behaviours and therefore make the perfect subjects to test whether simple brains can complete complicated tasks.

'Archerfish are a species of tropical freshwater fish that spit a jet of water from their mouth to knock down insects in branches above the water. We positioned a computer monitor that showed images of human faces above the aquariums and trained them to spit at a particular face. Once the fish had learned to recognize a face, we then showed them the same face, as well as a series of new ones.

'In all cases, the fish continued to spit at the face they had been trained to recognize, proving that they were capable of telling the two apart. Even when we did this with faces that were potentially more difficult because they were in black and white and the head shape was standardized, the fish were still capable of finding the face they were trained to recognize.

'The fact that archerfish can learn this task suggests that complicated brains are not necessarily needed to recognize human faces. Humans may have special facial recognition brain structures so that they can process a large number of faces very quickly or under a wide range of viewing conditions.'

Human facial recognition has previously been demonstrated in birds. However, unlike fish, they are now known to possess neocortex-like structures. Additionally, fish are unlikely to have evolved the ability to distinguish between human faces.

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15 comments

I worked with topical fish for a lot of years, and yes I think they can see me as there feeder and care giver. That person feeds me he is my reason I live ! Kind of simple I know, but, we are talking about fish.

Still, we must not forget the fact that mother-nature is a violent place... It is better to be the eater than the one who gets eaten. If you turn into an overly-loud treasonous softy-vegan educating us wrong- then you will cause your entire species to die. Your body cannot sustain its structure as designed (by some random big-bang or whatever) without consuming proteins found in the food our species has always eaten. Study some nutrition-science before you turn all "activist" against us. People are getting tired of your nonsense.

A friend of mine had a paku for twenty plus years, they are long-lived. There is no question that the paku recognized its owner. If fish had some version of Physorg, there would be a piece entitled, "People, as dense as they are, finally realize that fish can recognize them."

How do you distinguish between your face and your butt, AGreatWanker? What you spew, looks like, it smells like, it came from a butt. Looking at other threads, I have to ask, "Do you only reason with your backside?"

built a tropical fish store, they really knew me, I feed them and they know that. Fish know faces and a lot more, I had a blue eyed pecko. he loved being pet on the nose. I would dip my finger in to his tank and he would rise and put his nose there. Fish are not sentient but they know there environments so that gives rise to, yes that they may think. You know what you know, things are really not what they always seem to be. I ran a topical fish shop for 7 years, and these fish seemed to know me.

They recognize our faces, yet they cannot communicate with us their desire to be free; live a fishy life in a natural environment; and sadly, humans are too stupid and vain to see this plain truth and preserve their habitat and freedom for their own sake.

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